Displaying the number of available shots (that is, the number of remaining shots) is a technology often employed in an image-shooting apparatus, and this technology is used to display to a user how many pictures can still be taken when shooting. Currently, the method for determining the number of available shots generally includes: acquiring the size of remaining storage space M of the image-shooting apparatus, acquiring a size of space P required by each picture in a current scenario, and calculating an estimated value of the number of available shots N=M/P. The size of the space P required by each picture may be affected by many factors, such as resolution, compression ratio, and effect, that is to say, the size of the space P required by each picture varies in different shooting modes. Therefore, how to acquire the size of the space P required by each picture in different shooting modes becomes a difficult problem for determining the number of available shots currently.
In the prior art, to solve the problem for acquiring the size of the space P required by each picture, the size of the space P required by each picture is pre-estimated according to image parameters set in each shooting mode, correspondence between the shooting mode and the size of the space P required by each picture in the shooting mode is preset in the image-shooting apparatus, and the preset size of the space P required by each picture is used in calculating the number of available shots each time; however, an actual size of each shot picture may not be the same as P, so an error may exist in the calculated number of available shots, and precision is not high.